Improvement in coating iron or steel with copper or brass



Tfinitnl sna patent mil tia.

GEORGE JAMES HINDE, OF "WOLVERHAMPTON, ENGLAND.

Letters Patent Jo. 94,492, dated September 7, 1869; patented in England, February 26, 1869.

IMPROVEMENT IN COATING- IRON OR STEEL WITH COPPER OR BRASS, OR OTHER ALLOYS OF COPPER.

The Schedule referred to in these Letters Patent and making part of the same.

T 0 all tou'lw'm it may concern Be it known that I, GEORGE James Huron, of

\Volverhampton, in the county of Stafford, England,

, thereof; that is to say My invention consists of the improvements hereinafter described, in coating iron or steel with copper or brass, or alloys of copper, by which improvements the coating -of the iron and Steel is effected at acompara tively low temperature, and the ditliculiies which occur from the high temperature ordinarily required for eifecting the said coating are avoided.

My invention is especially applicable to the coating of sheets of iron and steel with copper or brass, or certain other alloys of copper, but is also applicable to the coating of various articles of iron or steel, either in a manufactured or partly-manufactu-red state, such as wir e bars, or rods, tubes, or vessels.

My invention is especially applicable to the coating of iron or steel with copper or brass, or alloy of copper and 'zinc, but is also applicable to the coating of iron or steel with copper alloyed with other metals than zinc, such as an alloy of copper with tin or with lead.

I will describe my invention, with reference to the coating of iron or steel with copper or b ass.

I clean the sheets or articles to be,coatcd by any of the well-known pickling 01' other processes ordinarily employed for that purpose, and l plunge the sheets or articles into a hath of melted zinc, containing copper in alloy with the said zinc, the quantity of zinc being so large, compared with that of the copper, as not to materially affect the color of the zinc. From iive to six parts, by weight, of zinc, to one part, by weight, of copper, I'iind to answer well in practice, but I do not limit myself to these proportions.

After a short immersion of the iron or steel sheets or articles in the said bath, they are withdrawn and cXposcd to heat in a mutlic or heating-cliainber, sufliciently hot to volatilize the zinc, and the sheets or articles are allowed to remain in the said muiiie or heating-chmnber until so much of the zinc has been volatilized as to leave brass upon the sheets or articles, or when a coatingof copper is required, the sheets or articles are allowed to remain in the .nutiie or heatingcha-mber until the whole, or nearly the whole of the zinc has been olatilized.

In order to prevent the sheets or articles from adhering together, or receiving any injury to their coatiug,1 prefer, before putting them in the mufiie or heating-chamber, to coat them with a mixture of finely-ground calcined flint and Water. This coating, when dry, protects the surface of the metal, and does not prevent the volatilization of the zinc.

After the sheets or articles are removed from the mnflie or heating-chamber, the coating of powdered flint is removed.

The articles are finished by burnishing or otherwise, and I prefer to pass the sheets that have been coated according to my invention, through a pair of plain rolls, in order to give smoothness to the coating.

Instead of proceeding in the manner described, the

sheets or articles to be coated with copper or brass may first receive a-coating of zinc, by the ordinary galvaniziiig-process, or they maybe coated with tin or terms metal before being plunged into the bath of'zinc and copper. A coating of copper alloyed with tin, or an easily-fused metal other than zinc, may be applied to sheets and articles of iron or steel, by a process similar to that already described, excepting that tin, or the other easily-fused metal, is to be employed in addition to the zinc.

Having explained generally the nature of myinvention, I willprocced to describe more in detail the manher in which the same is to be carried into efi'ect.

For convenience of description, I will describe my invention as applied to the coating of iromalthough it must be understood that both wrought and cast, and mallcablecast-iron and steel may be coated with copper, brass, or other alloy of copper, by my invention.

I first make. the surface of the iron to be coated perfectly clean. This I effect either by the process called pickling, that is, immersion of the iron in dilute sulphuric acid or muriatic acid, a process well understood and commonly practised, or by mechanical abrasion of the surface by scouring, filing, turning, or other mechanical operation. I

I prefer to dip the cleaned iron into a solution of sa-l-ammoniac before proceeding to coat itwith the alloy of copper. The iron, on removal from the said solution, is coated with a thin film of sal-anflnoniac. A solution of one pound of sal-ammoniac to one quart of water, answers very well for this purpose, but other proportions may be employed.

In making a bath of melted zinc and copper, which I will hereinafter call the coating-bath, I melt one part, by weight, of copper, in a crucible or melting-pot, and add thereto five parts, by weight, of zinc.- The melted metals, on being stirred, immediately form an alloy, and the coating of the iron may be eii'ccted by plunging it, prepared in the manner hereinbefore described, into the melted alloy contained in the crucible or melting-pot in which it is made. I prefer, however, to transfer the melted alloy into a bath or vessel, similar to that used for galvanizing iron, set in a furnace, and heated to a temperature sufficient to keep the alloy in a state of peifect fusion.

Before immersing the iron to be coated into this coating-bath, I prefer to throw some sal-z'nnmoniac on the surface of the coating-bath, and to introduce the iron to be coated through the layer of sal-ammoniac on the coating-bath. The iron, on being plunged into and withdrawn from the coining-bath,will be found to have received a coating of the alloy.

The quantity ofsal-mhmoniac which I prefer to throw on the surface of the coating-bath, previous to the immersion of the iron, varies from a few ounces to a few pounds, according to the size of the iron to be. coated. As the said sal-ammoniac volatilizes rapidly at the temperature of the coating-bath, I prefer to add it to the'bath immediately before the immersion of the iron therein. I

- I also add zinc to the coating bat-h from time to time, in order to replace that lost by volatilizing.

Although for ordinary purposes I effect the coating in a manner already described, yet the said coating may be effected upon iron, which has previously received a coating of zinc, or of tin, or of tin and lead, commonly called terne metal.

In coating, according to my invent-ion, iron which has received a preliminary coating of zinc or tin or terne metal, I proceed in the manner already described,

excepting that the cleaning and immersion in a solution -of sal-ammoniac are Unnecessary.

When the iron has received a preliminary coating of tin or terne metal, the composition of the coatingbath is liable to be affected thereby, the coating-bath becoming charged more or less with tin or tin and lead, and the proportion of copper relatively diminished. In such cases, I add to the coating-bath from time to time small portions of melted copper or of brass, in addition to the zinc added from time to time, so as to keep the proportion of copper in the bath, as n'earlyas may be, the proportion of one part of copper to five parts of zinc, or the other metal or metals.

Where it is wished to coat the iron with an alloy'of copper and tin, or copper and come metal, I- coat the iron first with tin or with tcrne metal, in the ordinary manner, and I plunge it into and quickly withdraw it fi'om the coating-bath.

In this way, the iron is coated with the alloy of zinc and copper upon the coating of tin or terne metal, more or less of the said coating of tin or terne metal being removed from the iron during its immersion in the coating-bath. Or I add the required amount of tin or terne metal to the coating-bath, and introduce the uncoated iron therein in the same man-' ner as when a coating of copper or brassis to be given to the iron. I prefer, however, in all cases where practicable, to use iron witho it any preliminary coating, and to make the coating-bath of the exact com- ..position which it is wished the coating to be given to the iron shall have previous to the heating-process hereinafter described.

The preliminary coating of zinc, or tin, or terne metal, is principally useful where small articles or articles of complex form are to be coated with copper or alloy of copper.- In such cases there is no risk of the coating failing in any part through oxidation of the iron-or steel, as sometimes happens when the iron or steel has not received a preliminary coating.

The iron, after immersion and removal from the coating-bath, is coated with a thin coating of the zinc and copper alloy, or when the iron has been previously coated with tin or with terne metal, the coating contains", besides zinc and copper a portion of tin or terne metal. The coating on the iron, after removal from the coating-bath, muchrescmbles a coating of zinc,

being of a nearly white color, and giving little or no indi ation by its color of the presence of copper. I will hereinafter call the iron in this stage alloy-coated iron.

1 next proceed to volatilize so much of the zinc of the alloy-coated iron as to produce a coating of brass or copper, or copper more or less alloyed with zinc, in the tbllowing manner: I place, in a vessel 'of convenient size and shape, a mixture of ground calcined flint and water, mixed to about the consistency of cream, and I immerse the alloy-coated iron in the said mixture,

,and innnediately withdraw it therefrom. A coating. of flint and water adheres to the said iron. This coating is quickly dried by the application of heat on or in a stove or in any other convenient manner. The alloy-coated iron, thus coated with dried calcined ground flint, is then placed ,in a conveni'ently-shaped annealing-box or vessel of iron or other refractory material. The alloy-coated iron,-placml in the annealing-box or vessel, is covered by another box or vessel, somewhat smaller, but of the same shape, invert-ed in the larger box. or vessel, the space between the sides of the smaller box or vessel and those. of the larger box or vessel being filled with dried calcined powdered flint. The box or vessel containing the alloy-coated iron is then placed in an annealing-mutfle, and heated until it is at a bright-red hcat throughout. About twenty to thirty minutes exposure to this heat is usually sufficient to volatilize so much of the zinc of the alloy-coated iron that an alloy of copper and'zinc, in the proportions in which they form brass, is left on the iron. By prolonging the time of exposure to heat, more zinc is volatilized, until eventually the whole or nearly the whole of the zinc is driven off, and a coating of pure or nearly pure copper isleft on the iron. To volatilize the whole or nearly the whole of the zinc, about two hours exposure of the alloy-coated iron at a bright-red heat is usually suflicient. \Vherc large annealing-boxes are eiii iltn etl, a longer exposure to heat is required, and where a very high temperature is employed, the zinc is volatilized more rapidly.

If the iron that has been coated is in the form of bars, rods, or plates, and it is desired to have a smoother surface than it has when taken from the mufilc, or licatirig-chamber, it passed through rolls, the adhering ground calcined flint having been previously washed or brushed off; The iron may be softened, if required, after being rolled, by subjecting it to a dull-red heat. The coated iron is then scoured with sand' and water, and rapidly dried by heat, in or on a stove or other means.

\Vhen manufactured or partly-manniactured articles are coated by my invention, and it is wished to make the coated surface smooth, this is efl'ect-ed by the process of burnishing, planishing, spinning, or other mechanical treatment, as is well understood.

When \vire has been coated according to my invention, it may be drawn in the same manner as brass wire is drawn, and annealed during the drawing-process If the wire is to be worked into manufactured articles in a hard state, it must not be annealed after the final drawing, but if it is required to be used in a softened state, it must be annealed after the final drawin".

By using the. proportion of zinc to copper in the coating-bath hereinbeibre described, or thereabout, I avoid many difliculties that arise inattempting to coat iron with copper or brass directly, as the. mixture of copper and zinc that I use is very fusible, and can be kept melted by the application of heat in an iron vessel, in the same manner as molten zinc.

By the use of a coating of powdered flint to the alloy-coated iron, previous to the volatilization of the zinc, the surfaces of the coated iron are prevented from touching each other in the pans or vessels, and the coated surface is less oxidized or tarnished than when the alloy-coated iron is without the coating of powdered flint.

Although I prefer to use (-aleined powdered flint for the purpose dust-tilted, yet I do not limit myself thereto, as other finely-divided substane s may be employed; and although I prefer to give the ;tl]o \'t:oatell iron a coating of powdered fiint or other matter previous to introducing it into the Innttie', or heatingehambcr, yet the use oi the said coatin; of powdered flint or other matter may e dispensed with in earr vinginy invention into elieet, and other methods resorted to of keeping the sheets or articles apart during the volatilization of" the zinc.

Having now described the nature of my invention, and the nianner in whieh the same is to he. perlhrmed, I wish it to be miderstood that 1 do not limit myself to the precise details herein described, asthe same may be varied without departing from the nature of my invention;v but I claim as my invention-- The improvements hereinbefine described in coating iron or steel with copper or brass or other alloys of copper, that is to say, coating iron or steel with copper or brass, by giving to the said iron or steel a coat- 7e s fzi/ ing of an alloy of copper and Zine. the prepartionof zinein the said alloy being so great that the said alloy dition to copper or copper and-zine, tin or ternemetal.

Further, the use ot'a tilm ot'powderedcalcined flint; or other finch-divided substance, for protecting the alloy-coated iron or steel from injury and oxidation during'the volatiiization ol' the zinc or other volatile metal emttained in the. coating.

GIGUHGH JAMES lllNDl]. In. s.]

Witnesses:

GEORGE SHAW,

7 Cannonib'lrreet, .IZirmingh-zun. RICHARD SKERRETT,

7 Cannon Street, .I-iirmingham. 

